Data from: Effects of antibiotic resistance alleles on bacterial evolutionary responses to viral parasites

Antibiotic resistance has wide-ranging effects on bacterial phenotypes and evolution. However, the influence of antibiotic resistance on bacterial responses to parasitic viruses remains unclear, despite the ubiquity of such viruses in nature and current interest in therapeutic applications. We experimentally investigated this by exposing various Escherichia coli genotypes, including eight antibiotic-resistant genotypes and a mutator, to different viruses (lytic bacteriophages). Across 960 populations, we measured changes in population density and sensitivity to viruses, and tested whether variation among bacterial genotypes was explained by their relative growth in the absence of parasites, or mutation rate towards phage resistance measured by fluctuation tests for each phage. We found that antibiotic resistance had relatively weak effects on adaptation to phages, although some antibiotic-resistance alleles impeded the evolution of resistance to phages via growth costs. By contrast, a mutator allele, often found in antibiotic-resistant lineages in pathogenic populations, had a relatively large positive effect on phage-resistance evolution and population density under parasitism. This suggests costs of antibiotic resistance may modify the outcome of phage therapy against pathogenic populations previously exposed to antibiotics, but the effects of any co-occurring mutator alleles are likely to be stronger.

抗生素耐药性对细菌表型与进化具有广泛影响。尽管这类病毒在自然界中无处不在，且治疗应用领域当前备受关注，但抗生素耐药性对细菌应对寄生性病毒的响应所产生的影响仍不明朗。我们针对该问题开展实验研究：将8种耐药型大肠杆菌（Escherichia coli）基因型与1种突变型基因型暴露于不同病毒（裂解性噬菌体，lytic bacteriophages）中。在960个种群中，我们测定了种群密度与病毒敏感性的变化，并检验了细菌基因型间的差异是否可由其在无寄生状态下的相对生长速率，或是针对每种噬菌体通过波动试验（fluctuation tests）测得的噬菌体抗性突变率予以解释。研究发现，尽管部分耐药等位基因会通过生长代价阻碍噬菌体抗性的进化，但抗生素耐药性对噬菌体适应性的整体影响相对较弱。与之形成鲜明对比的是，常在致病种群的耐药谱系中被检出的突变型等位基因，对寄生状态下的噬菌体抗性进化与种群密度均具有显著的正向影响。这表明，抗生素耐药性带来的代价或可改变曾接触过抗生素的致病种群的噬菌体疗法疗效，而共存的突变型等位基因所产生的影响可能更为显著。